The present disclosure relates generally to the gloss inherent in the hardcopy of image data be it pictorial or text. More particularly, this disclosure relates to digital image data and the control of differential gloss when that digital image data is printed into hardcopy. In particular the disclosure relates to the reduction of undesirable differential gloss by the employment of halftoned clear toner.
The acceptance of electrostaticgraphic print engines by the graphic arts and commercial print market has heretofore been hampered by various problems, including among them a perceived image quality issue relative to differential gloss. Typical electrostaticgraphic prints, including traditional xerographic prints, usually display high gloss in high mass regions. In the mid-tone regions the image gloss on a glossy substrate reaches a minimum. This differential gloss between high mass and mid-tone areas is objected to by some users.
A typical approach in the past has been to reduce the gloss in the high mass areas through toner and fusing optimization. However, this kind of approach also reduces the overall image gloss at the same time. This in turn upsets another group of users who find the typical glossy appearance of xerographic prints desirable.
Therefore, as discussed above, there exists a need for an arrangement and methodology which will control gloss in general and allow for reduction of undesired differential gloss employed in the application of a clear toner overlay upon a halftone image hardcopy print. Thus, it would be desirable to solve this and other deficiencies and disadvantages as discussed above, with an improved methodology for the manipulation of inherent differential gloss.
The present invention relates to a method for the reduction of differential gloss in a halftone image hardcopy output by selecting a first halftone having a high apparent gloss characteristic and a second halftone having a low apparent gloss characteristic. The first halftone is directed to at least some portion of a clear toner overlay applied upon the halftone image hardcopy output and the second halftone is directed to the remaining portion of the clear toner overlay applied on the halftone image hardcopy output.
In particular, the present invention relates to a method for the reduction of differential gloss in a halftone image hardcopy by selecting a first halftone having a high apparent gloss characteristic and a second halftone having a low apparent gloss characteristic. A determination is also made of which areas of the halftone image correspond to potentially high gloss regions under normal printing conditions. The second halftone is directed to those portions of a clear toner overlay applied upon the halftone image hardcopy output determined as corresponding to potentially high gloss regions of the halftone image. The first halftone is directed to the remaining portions of the clear toner overlay applied upon the halftone image hardcopy output.
The present invention also relates to a method for the reduction of differential gloss in a halftone image hardcopy by selecting a first halftone having a high apparent gloss characteristic and a second halftone having a low apparent gloss characteristic. A determination is made as to which areas of the halftone image correspond to potentially high gloss regions under normal printing conditions and which areas of the halftone image correspond to potentially low gloss regions under normal printing conditions. The first halftone is directed to those portions of a clear toner overlay applied upon the halftone image hardcopy output as determined as corresponding to potentially low gloss regions and the second halftone to those portions of a clear toner overlay applied upon the halftone image hardcopy output determined as corresponding to potentially high gloss regions of the halftone image.
The present invention further relates to a method for the reduction of differential gloss in a halftone image hardcopy by selecting a first halftone having a high apparent gloss characteristic and a second halftone having a low apparent gloss characteristic. A median average gloss level is determined as existent across the halftone image. Then those image areas in the halftone image which are above the median gloss level are determined as well. The second halftone is then directed to those portions of a clear toner overlay being applied upon the halftone image hardcopy output determined as corresponding to areas above the determined median gloss level of the halftone image. The first halftone being directing to the remaining portions of the clear toner overlay applied upon the halftone image hardcopy output.
The present invention further relates to a method for the reduction of differential gloss in a halftone image hardcopy output by selecting a single halftone providing at least two or more levels of physical area coverage and determining which areas of the halftone image correspond to regions of high and regions of low gloss under normal printing conditions. Then while applying a clear toner layer employing the selected single halftone to the printed hardcopy output of the halftone image, the local amount of applied clear toner is controlled in the determined areas by employing the correct level of the at least two or more levels of physical area coverage as provided by the selected single halftone.